The latest sex scandal threatening Silvio Berlusconi has deepened after a 17-year-old Moroccan belly dancer linked to the Italian prime minister said he had given her €7,000 and jewellery when she sat next to him at a Valentine's Day dinner held this year for 10 women at his mansion near Milan.

The girl, named in the Italian media as Karima Keyek but known more widely by her stage name Ruby Rubacuori, or Stealer of Hearts, denies sleeping with Berlusconi.

"It the first time in my life that a man has not tried to take me to bed. He behaved like a father, I swear," she told La Repubblica from Genoa, where she is hiding out in an apartment allegedly lent to her by a former porn star.

But she has painted a vivid portrait of private parties held by the 74-year-old prime minister, known by the Italian media as lavish affairs that often transformed into "bunga-bunga" sessions involving after-dinner sex between male and female guests.

In La Repubblica yesterday, Keyek said her host had told her not to come to see him any more after discovering she was not, as she had claimed, 24. "Berlusconi said he had had enough problems in the past with another underage girl," she said.

Keyek told Oggi magazine: "Silvio took me upstairs. He wanted to help me. He told me that he wouldn't ask anything in return.

"He gave me an envelope with €7,000 in it and I told him I dreamed of gaining Italian citizenship and becoming a policewoman." She told La Repubblica: "It was like going to the church charity where they give you a bag of shopping."

Last year Veronica Lario, the premier's second wife, accused him of "frequenting minors" and announced she was leaving him after he attended the 18th birthday party of aspiring model Noemi Letizia. Berlusconi claimed to be an old friend of the girl's family. His popularity was boosted by the rescue effort in earthquake-stricken Abruzzo. He also managed to shrug off later claims by escort Patrizia D'Addario that he had slept with her.

The new revelations echo lurid tales of Berlusconi's gifts of jewels and cash to women at the parties D'Addario attended in Rome in late 2008. But they come amid a slump in his approval ratings sparked by the defection of his ally Gianfranco Fini, a rise in unemployment and the return of the Naples rubbish crisis, which he claimed to have solved.

The revelations have once again sparked speculation about his fitness to lead: Catholic magazine Famiglia Cristiana queried his mental health on Friday, referring to his wife's fear that he had an "uncontrollable" illness, "permitted, or even encouraged, by his power and his enormous wealth".

Confronted last week by the media furore over the latest scandal, Berlusconi has tried to laugh off criticisms of his lifestyle. "I am a playful person, full of life. I love life, I love women," he said. But he has denied the part of the scandal reportedly of most interest to prosecutors: claims that he pressured Milan police to release Keyek when she was arrested on suspicion of stealing €3,000 from a friend in May.

Yesterday the respected Corriere della Sera newspaper reported that Berlusconi had personally informed a senior police official that Keyek was related to Egypt's President Hosni Mubarak. Berlusconi says he merely told police he was dispatching a colleague to take temporary custody of Keyek should she be released.

Berlusconi sent Nicole Minetti, a half-English TV showgirl turned dental hygienist who reportedly caught Berlusconi's eye when she treated his teeth and was made a regional councillor for his Freedom People party in March. "The girl had recounted a tragic story involving fleeing from shelters and finding herself in the street with her suitcases. Berlusconi stepped in," Minetti told the Observer.

Brought up in Sicily, Keyek says she ran away from home when her father announced an arranged marriage for her with a 49-year-old man, a claim her father denies. In Milan she met showbusiness agent Lele Mora, who reportedly introduced her to Berlusconi's circle. Mora, Minetti and Emilio Fede, a TV presenter and Berlusconi confidant, are all being investigated for alleged aiding and abetting of prostitution.

For her part, Keyek has said she is now intent on writing an autobiography with a chapter devoted to her relationship with her former dinner host. There are many people who would like to see her tell the full, unexpurgated tale.

"I am not surprised at all by this story. It is the same thing a year on, and my advice to Ruby is tell the whole truth right now," D'Addario told the Observer, claiming that the system of sex and favours she exposed in Berlusconi's inner sanctum showed no sign of waning. "He still likes women and they still want a future in TV or politics. It's a winning combination."